An artificial disc replacement surgery is an effective way of treating degenerative disc diseases, and it gradually replaces the commonly-used spinal fusion surgery. The artificial disc replacement surgery has beneficial effects of restoring disc space height, decreasing stress concentration in adjacent segments, keeping a range of a joint motion (ROM) between adjacent vertebrals, preventing the degeneration of the zygapophyseal joint, and so on. The artificial disc replacement surgery uses a movable artificial disc as an implant to replace the natural disc and achieve moving function.
A common artificial disc mainly includes an upper joint and a lower joint which are fixedly connected to their adjacent segments (adjacent vertebral sub-endplate bone/adjacent vertebral bone), respectively. A ball-socket structure is disposed between the upper joint and the lower joint. The artificial discs are movable as soon as they are implanted into disc spaces, and thereby ensure achieving the beneficial effects above. However, since the upper and lower joints of the artificial disc are fastened to their adjacent segments mechanically at first, a period of time is needed to achieve stable combination between the upper and lower joints and their adjacent vertebral sub-endplate bones (such a stable combination is called biological fixation hereinbelow). Namely, the biological fixation is achieved by performing the mechanical fixation to embed a spike of the artificial disc into a vertebrae, and performing a surface processing to the artificial disc, so as to make sclerotin grow into the combination (contacting) surface of the artificial disc. Before the sclerotin grows into the combination surface of the artificial disc, the combination surfaces of the upper and lower joints of the artificial disc and the adjacent vertebral sub-endplate bones are unstable due to a relative movement between the upper joint and the lower joint. As a result, the combination between the upper and lower joints and the adjacent vertebral sub-endplate bones is delayed or fails at all. Therefore, clinical reports about the artificial discs currently on the market often show occurrence of a displacement or even a dislocation of the artificial disc, as well as a related submergence of the artificial disc.